Image display device

ABSTRACT

A single plate type optical unit and display device to utilize light with high efficiency in a simple method is configured so a dichroic mirror separates light into a plurality of colors, and the plurality of colors of light reflected by the dichroic mirror are beamed onto a rotating multisurface element, the plurality of colors of light emitted from the rotating multisurface element are each beamed onto different locations on the display element, and by rotating the rotating multisurface element, the plurality of colors of light are moved in one direction along the display element, and a color image is beamed from a projection lens.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to projection devices such as liquidcrystal projectors, projection image display devices and optical enginessuch as reflective image display projectors and beam type rearprojection television for projecting images on a screen using lightvalve devices such as liquid crystal panels or image display elements,and relates in particular to technology for beaming a plurality of lightcolors onto different light valve element locations using a rotatingmultisurface element, and changing the beaming locations in sequence.

2. Description of the Related Art

An optical unit is known in the related art for passing light from alight source through a first and a second array lens, a polarized beamsplitter (PBS) and a collimator lens, and then separating the light intored light, blue light and green light by using a plurality of dichroicmirrors, and then changing the optical paths of each separated (colored)light by means of respective rotating prisms and beaming each light ontorespectively different locations on a light valve element (hereaftersimply referred to as a display element or image display element) andalso scroll each light beam in sequence in a fixed direction on thedisplay element locations.

SUMMARY OF THE INVENTION

The above described optical unit of the related art possessed theadvantage that assembly of the single plate utilized by the displayelement was simple. However the optical unit had to be made large insize since a plurality of prisms were required. Further, besides havinga high price due to use of a plurality of rotating prisms, a largenumber of lenses and many dichroic mirrors, the light utilizationefficiency was poor because of the many lenses that were used. Also, therotation phase of a plurality of rotating prisms had to be aligned inorder to adjust the display element positions upon which the red, greenand blue light were beamed and this alignment was difficult.Furthermore, noise prevention methods were needed due to the pluralityof motors being used.

The present invention therefore has the object of providing a compactand low-priced optical unit.

Another object of the present invention is to provide novel andeffective image display technology, allow simple position alignment fora plurality of light beamed onto a display element, and provide goodlight utilization efficiency.

To achieve the above objects of the invention, the optical unit iscomprised of a light source, a display element to form an optical imageaccording to an image signal from the light emitted from the lightsource, a light color separator means for separating the light emittedfrom the light source into a plurality of light colors, a rotatingmultisurface element input with a plurality of light colors emitted bythe light color separator means for changing the optical path andbeaming the plurality of light colors onto different locations on thedisplay element while scrolling the light beam in one direction, and aprojection device to light emitted from the display element as a colorimage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is structural views showing the first embodiment of the opticalunit of the invention.

FIG. 2 is perspective views of the display element for describing thestatus of the beam of three-colored light on the display element.

FIG. 3 is structural views showing the second embodiment of the opticalunit of the invention and a flat view of the display element.

FIG. 4 is structural views showing the second embodiment of the opticalunit of the invention and a flat view of the display element.

FIG. 5 is structural views showing the second embodiment of the opticalunit of the invention and a flat view of the display element.

FIG. 6 is a structural view showing the first embodiment of the displaydevice of the present invention.

FIG. 7 is structural views showing the third embodiment of the opticalunit of the present invention.

FIG. 8 is structural views showing the fourth embodiment of the opticalunit of the present invention.

FIG. 9 is structural views showing the fifth embodiment of the opticalunit of the present invention.

FIG. 10 is structural views showing the sixth embodiment of the opticalunit of the present invention and a flat view of the display element.

FIG. 11 is structural views showing the sixth embodiment of the opticalunit of the present invention and a flat view of the display element.

FIG. 12 is structural views showing the sixth embodiment of the opticalunit of the present invention and a flat view of the display element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention are hereafter described whilereferring to the work drawings.

FIG. 1 is structural views showing the first embodiment of the opticalunit of the invention.

In this figure, the light emitted from the light source 1 obtained afterreflection from a reflector is input to a first array lens 2 for forminga plurality of secondary light source images, and then passed through asecond array lens 3 formed by a plurality of focusing lenses andinstalled in the vicinity of the second light source image, for forminglens images for each of the first array lenses 2 in the liquid crystaldisplay element 12. The mixed light of P polarized light and S polarizedlight that passed through the second array lens 3, the S polarized lightfor example is aligned by the polarized beam splitter 4 (hereafterreferred to simply as PBS) and the λ/2 wavelength plate 4 a, and passedthrough the first collimator lens 5 a and second collimator lens 5 b andthe light respectively reflected as red light, green light and bluelight by the red dichroic mirror 7 a for reflecting red light, the greendichroic mirror 6 b for reflecting green light, and the B dichroicmirror or reflecting mirror 7 c (hereafter referred to as dichroicmirror group) for reflecting B light. The red light, green light andblue light respectively pass through the third collimator lens 5 c, andirradiate different locations on the respective reflecting rotatingpolygonal mirrors 43, and are reflected from the reflecting rotatingpolygonal mirrors 43. In this embodiment, the reflecting rotatingpolygonal mirrors 43 has eight surfaces however there is no restrictionon the number of surfaces. The dichroic mirror group 7 a, 7 b, and 7 cin this embodiment is the three colors red, blue and green. However acombination of red, green blue and white, or yellow, cyan, magenta, or acombination of yellow, cyan, magenta or a combination of red, yellow,green cyan and magenta, or red and orange, or green, blue and violet maybe used. In such cases, the dichroic mirror group constituting the colorseparator means may consist of a plurality of plates such as three ormore plates. In this case, the scroll zone on the display element may bethree or more types.

In the case of two-plate type optical unit (each plate installedrespectively on one of the two surfaces of a cube type PBS utilizing 2display elements), a structure may be used where only the scrollinglight arrives on the first display element via the rotating polygonmirror, and the remaining non-scrolling light is made to arrive directlyon the second display element by way of a fixed mirror and a lens.

When the red light, green light and blue light are reflected from onesurface of the reflecting rotating multisurface element 43, theirrespective optical paths intersect. When any of the red light, greenlight, and blue light are reflects as two lights from one surface of thereflecting rotating multisurface element 43, then the optical paths oftheir light intersect (related later on while referring to FIG. 4, FIG.5). The red light, green light and blue light emitted from thereflecting rotating multisurface element 43 pass through the converginglens 6, the condensing lens 8, and the polarizing plate 9 a and afterreflecting from the PBS 10, pass through the λ/4 wavelength plate 11 andare beamed on different locations on the display element 12. P polarizedlight converted from the S polarized light emitted from the displayelement 12 passes through the PBS10, and after further permeatingthrough the polarizing plate 9 b, is displayed as an enlarged image onthe screen (not shown in drawing) by way of the projection lens 13.

Any of a transmissible liquid crystal device, a reflecting liquidcrystal display element, a ferroelectric liquid crystal device as wellas a micro-mirror image display element may serve as needed, as thedisplay element of the present invention. In the present embodiment, thereflecting liquid crystal display element or the ferroelectric liquidcrystal device can be used as the display element 12.

In the embodiment of FIG. 1, the optical paths of the red light, greenlight and blue light reflected by the dichroic mirror group 7 a, 7 b, 7c are aligned so that the red light, green light and blue light arebeamed onto the specified locations on the display element 12. Also, thesize and number of rotating polygonal mirrors is determined so that whenthe rotating multisurface element 43 has rotated these optical paths,the red light, green light and blue light can be moved at approximatelythe same speed in one direction.

Further, a combination of dichroic prisms and reflecting mirrors can beused instead of the dichroic mirror group 7 a, 7 b, 7 c, to separate thered light, green light and blue light and control the optical axis withreflecting mirror.

The light beam (irradiation) status of the red light, green light andblue light at the time of reflection from the reflecting rotatingmultisurface element 43 onto the display element 12 is next describedwhile referring to FIG. 2.

FIG. 2 is an oblique view of the display element for describing thebeaming of the three color light on the display element. In FIG. 2, 12Ris the location where the red light is beamed upon, 12G is the locationwhere the green light is beamed, and 12B shows the location where theblue light is beamed. The blue light, green light and red light arebeamed upon the display element 12 simultaneously. Here, 21R, 21G and21B are respectively the locations where the red light, green light andblue light are next beamed, and the address for beaming the red light,green light and blue light is performed. The size of that location isdetermined by the write time of the display element 12, namely, theresponse time of the display element 12 and the scroll speed so thateven one line is sufficient when the response time is sufficientlyfaster than the movement time for scrolling one line. When the responsetime is slow, a number of lines is assigned to match that response time.

When first beaming these lights from above by scrolling along thedisplay element 12, each color is written in sequence from above, asinformation matching each color in the respective address in locations12R, 12G and 12B, and the red light, green light, blue light is thenbeamed in sequence from above on each color area on the display element12. During that time, addresses are written in the locations 21R, 21Gand 21B. When the address writing in the locations 21P, 21G and 21B iscomplete, the red light, green light, blue light beaming on therespective locations 12R, 12G and 12B moves downward along the displayelement 12 just by an amount corresponding to the locations 21R, 21G and21B, and red light, green light, blue light beams (irradiates) on thelocations 21R, 21G and 21B. When writing in the locations 21R, 21G and21B is complete, address writing is then performed on the lower line.The locations irradiated by the red light, green light and blue light inthis way move downward in sequence.

The size of the locations 12R, 12B and 12B are approximately the same inthis embodiment, so the lens shapes of the first array lens 2 are formedto resemble the light band shape of the red, green or blue light beamingon the locations 12R, 12G and 12B on the display element 12.

The second embodiment of the present invention is next described whilereferring to FIG. 3 through FIG. 5.

FIG. 3, FIG. 4 and FIG. 5 are structural views showing the secondembodiment of the optical unit of the invention and flat views of thedisplay element. FIG. 3A, FIG. 4A and FIG. 5A are structural views ofthe respective optical units. FIG. 3B, FIG. 4B and FIG. 5B are showlocations on the display element irradiated by the red light, greenlight and blue light. In the figure, when the reflecting rotatingmultisurface element 43 is rotating in the direction of arrow A. FIG. 3Ashows the embodiment when the red light, green light and blue lightreflected by the dichroic mirror groups 7 a, 7 b, 7 c is beamed upon onesurface of the reflecting rotating multisurface element 43. In thiscase, as shown in FIG. 3B, the locations irradiated by the red light,green light and blue light, are 12R, 12G and 12B in sequence from leftto right on the display element 12. The embodiment in FIG. 4A shows thecase when the red light and green light reflected by the dichroic mirrorgroups 7 a, 7 b, 7 c from among the red, blue and green light, arebeamed upon one surface, and the blue light is beamed upon the nextsurface. In this case, as shown in FIG. 4B, the locations beamed upon bythe red light, green light and blue light, are 12B, 12R and 12G insequence, from the right, on the display element 12.

In the embodiment shown in FIG. 5A, only the red light from among thelight reflected by the dichroic mirror groups 7 a, 7 b, 7 c is beamedupon the surface, and the green light and blue light is beamed upon thenext surface. In this case, as shown in FIG. 5B, the locations on whichthe red light, green light and blue light is beamed, are the locations12G, 12B and 12R in sequence from the right on the display element 12.

Sections in FIG. 3 through FIG. 5 assigned with the same referencenumerals are identical to the same sections in FIG. 1 so an explanationis omitted here. In FIG. 3 through FIG. 5, the point differing from FIG.1 is that, the λ/2 Wavelength plate 4 a, and the second collimator lens5 b are omitted on the optical path from the light source 1 to thedichroic mirror group 7 a, 7 b, and 7 c. The third collimator lens 5 cis eliminated from the optical path from the dichroic mirror group 7 a,7 b, and 7 c to the reflecting rotating multisurface element 43 and aconvergence lens 6 a is used instead. The optical path has the samestructure from the reflecting rotating multisurface element 43 to theprojection lens 13. This embodiment operates the same as the embodimentof FIG. 1, and along with red light, green light and blue light beamingonto the respective locations 12 a, 12 b and 12 c on the display element12, those locations are moved in sequence in one direction on thedisplay element 12, and a color image can be displayed on a screen (notshown in drawing) on one display element 12.

FIG. 3 shows the case when the red light, green light and blue lightreflected by the dichroic mirror group 7 a, 7 b, and 7 c arerespectively converged on one surface of the reflecting rotatingmultisurface element 43. In this case, the optical axes of the redlight, green light and blue light reflected from the reflecting rotatingmultisurface element 43 intersect between the light beam input surfaceof the PBS10 and the reflecting rotating multisurface element 43. Theexample in this embodiment described an eight surface element but thereis no restriction on the number of surfaces.

When red light and green light are beamed upon one surface of thereflecting rotating multisurface element 43, and blue light is beamed onthe next surface as shown in FIG. 4, the green light and red light arethen beamed on the PBS10, after the optical axes of the green light andthe red light reflected from the reflecting rotating multisurfaceelement 43 intersect each other, however the optical axis of the bluelight does not intersect with the axes of the red light and green lightand is input to the PBS10.

When the red light is beamed upon one surface of the reflecting rotatingmultisurface element 43, and the green light and blue light are beamedon the next surface as shown in FIG. 5, the light is beamed onto theinput surface of the PBS10 after the optical axes of the green light andblue light reflected from the next surface of the reflecting rotatingmultisurface element 43 have intersected each other.

It can be seen from the above description that when a plurality of lightcolors are beamed upon one surface of the reflecting rotatingmultisurface element 43, the light is beamed into the PBS10 after theoptical axes of the plurality of light reflected from the reflectingrotating multisurface element 43 intersect.

The embodiment of the display device of the present invention isdescribed next.

FIG. 6 is a structural view showing the first embodiment of the displaydevice of the present invention.

Sections in FIG. 1, and FIG. 3 through FIG. 5 assigned with the samereference numerals are identical to the same sections in this figure soan explanation is omitted here. In this embodiment, the optical pathfrom the light source 1 to the dichroic mirror group 7 a, 7 b, and 7 cis the same as the embodiment of FIG. 1, and the optical path from thedichroic mirror group 7 a, 7 b, and 7 c to the projection lens 13 is thesame as the optical path in FIG. 3 through FIG. 5. The operation of theoptical unit of this embodiment is also the same as in FIG. 1 and FIG. 3through FIG. 5 so that a color image can be shown on the screen (notshown in drawing) by the beaming of light from the projection lens 13.

In the embodiment of FIG. 6, the reference numeral 24 denotes a powersupply, the reference numeral 25 denotes an image display circuit forprocessing image signals and the reference numeral 26 denotes an exhaustfan, and the image display device is comprised by mounting thesecomponents in an optical unit having an optical path from the lightsource 1 to the projection lens 13.

The embodiment when the direction from the light source 1 to thedichroic mirror group 7 a, 7 b, and 7 c is the same as the directionfrom the reflecting rotating multisurface element 43 to the projectionlens 13 is described next while referring to FIG. 7.

FIG. 7 is structural views showing the third embodiment of the opticalunit of the present invention. Sections in the figure assigned with thesame reference numerals are identical to the same sections in theembodiments of FIG. 1 and FIG. 3 through FIG. 5 so an explanation isomitted here.

The optical path between the light source 1 to the dichroic mirror group7 a, 7 b, 7 c is different from the optical path shown in FIG. 1 in thatthere is no second collimator 5 b however the other components of theoptical path are the same.

In the optical path from the dichroic mirror group 7 a, 7 b, and 7 c tothe reflecting rotating multisurface element 43 is different from theoptical path shown in FIG. 1 in that there is no third collimator 5 c,however this collimator 5 c may also be used. Two types of converginglenses 6 a, 6 b are used in the optical path from the reflectingrotating multisurface element 43 to the PBS10. The structure from thePBS10 onwards is the same as shown in FIG. 1. The dotted line in FIG. 7indicates the green light, while the dot-dash line indicates the opticalaxis of the green light. The optical axes of the red light and bluelight are omitted but their optical axes can be shown as in FIG. 1.

In this embodiment, among the three (colors of) lights reflected fromthe dichroic mirror group 7 a, 7 b, and 7 c, the light in the center, orin other words the green light is focused and converged on one surfaceof the reflecting rotating multisurface element 43. In this case, thered light and the blue light are beamed centered around the green lighton the reflecting rotating multisurface element 43 so that each surfaceof the reflecting rotating multisurface element 43 can be made smallercompared to when the green light is converged onto other than the centerof the reflecting rotating multisurface element 43.

Also in the present embodiment, the red light, green light and blueprojected light can be emitted from the projection lens 13 on an opticalaxis approximately in parallel with the optical axis of the dichroicmirror group 7 a, 7 b, and 7 c from the light source 1.

There is no restriction here on the collimator lens and these may beinstalled behind the dichroic mirror group 7 a, 7 b, and 7 c. Theparticular features of the dichroic mirror group 7 a, 7 b, and 7 c mayalso be interchanged such as by either of the combinations of RGB, BGRhowever, weak light wavelengths should have priority according to theoutput of the light source serving as the light source, in other words,the initial reflection method is satisfactory for reducing the permeance(transmittance) count.

The fourth embodiment of the present invention is described next whilereferring to FIG. 8.

FIG. 8 is a structural view showing the fourth embodiment of the opticalunit of the present invention. In this figure, after the light from thelight source 1 has passed through the first collimator lens 5 a and thesecond collimator lens 5 b, the light is input to the first light valve46. The polarization direction of the light is aligned by the PBS45 a,PBS or the full reflecting prism or the full reflecting mirror 45 b, orthe λ/2 wavelength plate 4 b while reflecting from the internal surfaceof the first light valve 46 and advancing, and is input for example as Spolarized light to the second light valve 44. The S polarized lightinput to the second light valve 44 advances while reflecting from theinternal surfaces of the second light valve 44 and the red light, greenlight and blue light are respectively reflected from the dichroic mirrorgroup 7 a, 7 b, and 7 c and are input to the reflecting rotatingmultisurface element 43. The red light, green light and blue lightreflected from the reflecting rotating multisurface element 43 passthrough the first converging lens 6 a, second converging lens 6 b, thirdconvergence lens 6 c and polarizing plate 9 a and are input to thePBS10. The optical path from there onwards is the same as in the case ofFIG. 1.

A color image can also be displayed on the screen in this embodiment.Also in this embodiment, light projected from the projection lens 13 canbe emitted on an optical path in a direction perpendicular to theoptical axis of light from the dichroic mirror group 7 a, 7 b, and 7 cand light source 1.

In this embodiment, the light is formed into S polarized light by meansof the PBS45 a and the fully reflecting prism 45 b so that a line orstreak can be obtained between the S polarized light emitted from Spolarized light emitted from the PBS 45A and the S polarized lightemitted from the fully reflecting prism 45 b. When these two S polarizedlights pass through the second light valve 44, the line or streakoccurring among the two S polarized lights is eliminated by reflectionof the two S polarized lights internally in the second light valve 44.If not concerned with the line or streak occurring among the two Spolarized lights, then the second light valve 44 for aligning the Spolarized light may be omitted.

Insertion of the PBS45 a causes the width of the light of the lightvalve 46 to enlarge in one direction to approximately twice the originalsize so the shape of the output beam opening of the light valve 44 caneasily be made to a similar shape (band rectangular shape) as the scrollband shape on the display element. Also the input opening shape of thelight valve 46 can be designed to a shape (for example, an approximatelysquare shape) to match the light spot shape, so that light loss can belimited and the light can easily be extended to a rectangular shape andextremely good efficiency obtained. The output light beam opening of thelight valve 44 can also be made to reconverge light onto the displayelement without having to form a rectangular aperture so that there isno need to cutoff the light such as by using a rectangular aperture andthe efficiency is good.

When a micromirror type image display element is utilized as the displayelement 12 in this embodiment, there is no need to align the directionof the polarized light so that the PBS45 a, the fully reflecting prismor the fully reflecting mirror 45 b, and the λ/2 wavelength plate 4 bare not needed.

The fifth embodiment of the optical unit of the present invention isdescribed next.

FIG. 9 is structural views showing the fifth embodiment of the opticalunit of the present invention. In the figure, the dotted line indicatesonly the green light and the dot-dashed line indicates the green lightoptical axis. The optical axes of the other colors of light are the sameas for example in FIG. 1. Sections in the figure having the samereference numbers as in FIG. 1 have the element functions so adescription is omitted.

In this embodiment, the light from the light source 1 is input to afirst array lens 2 for forming a plurality of secondary light sourceimages, and passed through a second array lens 3 formed by a pluralityof focusing lenses installed in the vicinity where the plurality ofsecondary light source images are formed, and that converges each of thelens images of the first array lens 2 onto the liquid crystal displayelement 12. The mixed light of P polarized light and S polarized lightthat passed the second array lens 3 is aligned into S polarized light bythe polarized beam splitter 4, and by means of the first collimator lens5 a, the red light, green light and blue light are respectivelyreflected by the red dichroic mirror 7 a for reflecting red light, thegreen dichroic mirror 7 b for reflecting green light, and blue dichroicmirror or reflecting mirror 7 c for reflecting blue light (Anultraviolet permeable mirror may be used, and if the structure reflectsthe red light last, then may comprise an IR permeable mirror.). The redlight, green light and blue light irradiate onto respectively differentlocations on the reflecting rotating multisurface element 43 and arereflected by the reflecting rotating multisurface element 43. After thered light, blue light and green light reflecting from the reflectingrotating multisurface element 43 have passed through the secondcollimator lens 5 b, and been reflected by the reflecting mirror 16, theoptical path is changed approximately 90 degrees and passes through thecondenser lens 8. The red light, blue light and green light that passedthrough the condenser lens 8, passed through the first polarizing plate9 a, is reflected by the PBS10, passes through the λ/4 wavelength plate11 and is input to the reflecting type display element 12. The redlight, blue light and green light converted into P polarized light atthe display element 12, passes this time through the PBS10, and isoutput by the second polarizing plate 9 b. The optical axis emitted fromPBS10 is parallel to the direction of the light from the light source 1and is output facing opposite the light from the light source 1.

In this embodiment, an optical unit can be configured without using aconvergence optical system.

An example is next described using a transmissible rotating polygonalmirror in the optical unit.

FIG. 10, FIG. 11 and FIG. 12 are structural views showing the sixthembodiment of the optical unit of the present invention and flat viewsof the display element. FIG. 10A, FIG. 11A and FIG. 12A are structuraldrawings of the respective optical units. FIG. 10B, FIG. 11B and FIG.12B show locations on the display element irradiated by the red light,green light and blue light.

FIG. 10A shows the case when the red light, green light and blue lightirradiate (beam) onto one surface of the transmissible rotatingpolygonal mirror with optical paths of mutually different directions,and the red light, green light and blue light are emitted from a surfacefacing that one surface. The red light, green light and blue lightirradiate (beam) respectively in sequence from the top, onto thelocations 12R, 12G and 12B on the surface of the display element 12 asshown in FIG. 10B. The embodiment in FIG. 11, shows the case when thered light, green light and blue light irradiate (beam) onto two surfacesof the transmissible rotating polygonal mirror 43 from optical axes ofmutually different directions, and the red light, green light and bluelight are emitted from surfaces opposing (facing) those two surfaces. Asshown in FIG. 11B, the red light, green light and blue light isirradiated onto the locations 12G, 12B and 12R in sequence from above,on the surface of the display element 12. The embodiment in FIG. 12Ashows the case when the red light, green light and blue light irradiate(beam) onto two surfaces of the transmissible rotating polygonal mirror43 from optical axes of mutually different directions, and the redlight, green light and blue light are emitted from surfaces opposing(facing) those two surfaces, and as shown in FIG. 12B, the red light,green light and blue light irradiate (beam) in sequence from above, ontothe locations 12B, 12R and 12G on the display element 12.

In FIG. 10 through FIG. 12, the light from the light source 1 passesthrough the first array lens 2 and the second array lens 3, and thepolarity of the light is aligned by the PBS4, and passes through thecollimator lens 5 for example as S polarized light, and the red light,green light and blue light are respectively reflected by the reddichroic mirror 7 a for reflecting red light, the green dichroic mirror7 b for reflecting green light, and a blue dichroic mirror or reflectingmirror 7 c for reflecting blue light. The red light, green light andblue light reflected by the dichroic mirror group 7 a, 7 b, 7 c pass thetransmissible rotating polygonal mirror 47. The red light, green lightand blue light permeating through the transmissible rotating polygonalmirror 47, then passes through the condenser lens 8 and the firstpolarizing plate 9 a, is reflected by the λ/4 wavelength plate 11 and isinput to the reflecting type display element 12.

The red light, green light and blue light reflected at this displayelement 12 and polarized into P polarized light, passes the PBS10 and isinput to the projection lens 13. In this embodiment, the direction ofthe light emitted from the projection lens 13 is approximately parallelwith the direction of light emitted from the light source 1, and facesthe opposite direction.

In the embodiments in FIG. 10 through FIG. 12, the transmissiblerotating polygonal mirror 47 rotates clockwise (direction of arrow A) asseen in the drawing.

In FIG. 10, the red light, green light and blue light reflected by thedichroic mirror group 7 a, 7 b, 7 c on mutually different optical axes,are input to one surface of the transmissible rotating polygonal mirror47, pass through the transmissible rotating polygonal mirror 47, andafter being emitted from a surface facing the transmissible rotatingpolygonal mirror 47, these optical axes intersect and are input to thecondenser lens 8.

In FIG. 11, the transmissible rotating polygonal mirror 47 is rotatedclockwise in the case of FIG. 10, and the red light input to onesurface, and the green light and blue light input to the next surface,and the respective red light, green light and blue light pass thetransmissible rotating polygonal mirror 47, the red light is emittedfrom a surface different from the surface facing the one surface (of themultisurface element 47), the green light is input from the nextsurface, and emitted from a surface facing that surface, the blue lightis input from the next surface, and emitted from a surface differentfrom the surface facing that one surface. In this embodiment, the greenlight and blue light input from different surfaces, are emitted fromdifferent surfaces and after intersecting, are input to the PBS10.

In FIG. 12, the red light is input to one surface of the transmissiblerotating polygonal mirror 47, and the green light and blue light inputfrom the next surface, and the red light, green light and blue lightrespectively pass the transmissible rotating polygonal mirror 47. Thered light is output from the surface facing the next surface, the greenlight is output from the surface facing the one surface, and the bluelight is output from the surface facing the next surface. After the redlight and blue light output from the surface facing the next surfacehave intersected, they pass the condenser lens and are input to thePBS10.

In the embodiments from FIG. 10 through FIG. 12, at least two of the redlight, green light and blue light intersect after being output from thetransmissible rotating polygonal mirror 47.

In this embodiment, any material capable of permeating light can be usedas the material for the transmissible rotating polygonal mirror 47.Also, the number of surfaces of the transmissible rotating polygonalmirror 47 is not limited to eight surfaces and any polyangular shape canbe utilized if having three or more sides. There are further norestrictions on the size of the transmissible rotating polygonal mirror47.

The invention as described above can irradiate a respective plurality ofcolors on different locations on one display element by utilizing adichroic mirror group to separate and reflect light into a plurality ofcolors, and a rotating multisurface element to change the direction ofthis plurality of colors; furthermore, the locations irradiated (orbeamed upon) on the display element by the plurality of colors can besequentially changed in one direction by rotating the rotatingmultisurface element, so that a color image can be obtained using onedisplay element that further has a simple structure.

Also in this invention, the light from the light source is separatedinto a plurality of colors and this separated plurality of light colorscan be irradiated with good efficiency upon a display element so thatthe utilization efficiency of the light is good.

In this invention, only one rotating multisurface element is used sothat the positioning of the plurality of light colors irradiated uponthe display element is simple.

In this invention therefore, as described above, an optical unit havinga simple single plate type structure can be obtained. An optical unithaving good light utilization efficiency can be obtained. Further, anoptical unit having good simple positioning of the plurality of colorson the display element can also be obtained.

1-22. (canceled)
 23. An image display device comprising a light source,a reflecting image display element to form an optical image according toan image signal from the light emitted from said light source, a colorseparator which separates the light emitted from said light source intoa plurality of light colors, a rotating multisurface element beinginputted with each light color of the plurality of light colors emittedby said color separator which changes the respective optical axisdirection and beaming said each light color onto different locations onsaid reflecting image display element while scrolling the light in onedirection, a projection lens which projects light emitted from saidreflecting image display element as a color image light, and an opticalelement which changes shape of the light emitted from said light sourceinto approximately similar shape as the form of the each light color ofthe plurality of light colors Inputted onto said reflecting imagedisplay element, wherein the light changed by said optical element isinputted with said rotating multisurface element through said colorseparator.
 24. An image display device according to claim 23, whereinsaid optical element is constituted including at least one light pipe.25. An image display device according to claim 24, wherein the outputopening shape of said light pipe is designed to approximately similarshape as the form of the each light color inputted onto said reflectingimage display element.
 26. An image display device according to claim23, wherein said optical element is constituted including a plurality ofarray lenses which constituted ach plural lens cells and each array lensshape of the said plurality of array lenses is designed to approximatelysimilar shape as the form of the each light color inputted onto saidreflecting image display element.
 27. An image display device accordingto claim 23, wherein the light axes of each light color of the pluralityof light colors emitted by said color separator are inputted ontoapproximately vertically to one surface constituting said rotatingmultisurface element at predetermined rotating angle.
 28. An imagedisplay device comprising a light source, a color separator whichseparates the light emitted from said light source into a plurality oflight colors, a rotating multisurface element which reflects each lightcolor of the plurality of light colors emitted by said color separator,a reflecting image display element to form an optical image according toan image signal, based on the light emitted from said rotating multisurface element, a projection lens which projects light emitted fromsaid reflecting image display element as a color image light, and anoptical element which changes shape of the light emitted from said lightsource into approximately similar shape as the form of the each lightcolor of the plurality of light colors inputted onto said reflectingimage display element, wherein the light changed by said optical elementis inputted onto said rotating multisurface element through said colorseparator.
 29. An image display device according to claim 28, whereinsaid optical element is constituted including at least one light pipe.30. An image display device according to claim 29, wherein the outputopening shape of said light pipe is designed to approximately similarshape as the form of the each light color inputted onto said reflectingimage display element.
 31. An image display device according to claim28, wherein said optical element is constituted including a plurality ofarray lenses which constituted ach plural lens cells and each array lensshape of the said plurality of array lenses is designed to approximatelysimilar shape as the form of the each light color inputted onto saidreflecting image display element.